I used to DM for a group in high school and ran a great adventure that involved everyone being stuck in a dungeon with a machine that allowed the party to travel back and forth in time. It was a bit of work keeping track of things changing through the timelines but a great puzzle adventure. I would love to try it again now, but I have had no luck finding it.
What I remember of the adventure:
- It was in D&D 3.5e.
- The mechanism for time travel was a bridge in a cube-shaped room. The bridge could move, and you would walk to the other wall (and gravity would change for you and all); each wall was a different time period.
- There was a magic ‘elevator’ – essentially a hole you jumped down that would loop back up to the top with a portal. If you held the right beads, you would stop at the desired floor.